This ion generally relates to a color matrix reflective filter.
Various techniques are known for making three color, flat displays. In U.S. Pat. No. 4,807,978 issued Feb. 28, 1989 to Grinberg et al. color sensitive, holographic lens elements sensitive to different wavelengths of light are used to focus different wavelengths of light onto different corresponding target areas, while generally transmitting input light outside of their wavelengths of sensitivity. Disadvantageously, this approach results in significant loss of light intensity because of transmission attenuation and loss of unfocused light. In U.S. Pat. No. 4,686,519 issued Aug. 11, 1987 to Yoshida et al., lenticular and prism sheets are used to focus and diffract light into a spectrum that is refracted further to be coincident with corresponding light valves on a LCD. This system eliminates the standard absorption filters now commonly used, but again loses significant light intensity transmission. In U.S. Pat. No. 4,798,448 issued Jan. 17, 1989 to van Raalte, a lenticular screen and diffraction grating is used to split incident light into spectrum with red, green and blue components of light directed to corresponding pixels. A Brewster angle transparent plate system is used to provide monotonic polarization to light cells, but again significant amounts of light intensity are lost and the system is not well adapted for reflective displays.
Unfortunately, none of these systems are particularly well suited for back lit displays. Known back lit displays use absorbent light filter elements which transmit light only the color associated with the elements and absorb the remaining colors. This results in substantial inefficiency. This filter absorbs all elements of the light except the narrow band required for the particular pixel. In a full color matrix display, the filter is composed of sets of three color pixels. Each set consists of a blue, a green, and red pixel. A full panel may consist of hundreds or thousands of these sets arranged in rows and columns. When a panel covered with these elements is illuminated with a white light, only the red wavelengths pass through the red cell, the blue and green wavelengths are absorbed. Likewise, for the green and blue cells. Accordingly, less than one-third of the illuminating light actually is used to provide a colored display.